Ophthalmic lens protractor



5, 1950 E. w. LAlSNEi- 2,518,796

OPHTHALMIC LENS PROTRACTOR Filed May 24, 1945 2 Sheets-Sheet 1 fl- 1950 E. w. LAISNE 2,518,796

OPHTHALMIC LENS PROTRACTOR Filed May 24, 1945 2 Sheets-Sheet 2 Patented Aug. 15, 1950 UNITED STATES PATENT OFFICE OPHTHALMIC LENS PROTRA'CTOR Eugene W. Laisn, Fresno, Calif.

Application May 24, 1945, Serial N0. 595,528

;1 Claim. 1

My invention relates primarily to an ophthalmic lens protra ctor used in the final processing of eyeglass and other lenses.

In cutting and grinding of eyeglass lenses to a given prescription it is necessary that certain of power and these meridians are at right angles to each other. One of these meridians produces the greatest power and the other the least power =-0f the lens. y

In a cylindric curve the angle or slant of the f plane of the surface is expressed in degrees. The

,degree numbers indicate the position of the plane lof the cylinder as compared to the horizontal line of the lens as set in the frame or mounting. .This plane meridian is called the axis and the angle of the plane to the horizontal is determined l with the aid of a protractor.

Iihis instrument is usually a circle crossed with numerous degree lines radiating from the center to the outer edge and numbered at their outer ends to indicate the angle formed with the horijzontal or zero line.

' The position of the plane of the cylinder must .be considered in the laying out for spherical or cylindrical second side grinding with the plane .of the cylinder on the line of the protractor corresponding to the degree number or angle given as the axial meridian and a line drawn on the liens identical with the horizontal or zero line of .tharmotractor. This line will be the cutting v line or the long diameter of the lens in the' :.'shape it is to be Worn. "Heretofore the laying out or inscribing of these necessary lines has been performed"free hand @by laying the lens upon the protractor face and :attempting to inscribe a line upon the lens with afpen and ink in exact register with the desired iline upon the protractor. It is obvious that this procedure must of necessity be slow andrnor'e or jl'ess inaccurate resulting in improper iilling of 'the given prescription, which inturn necessitates" 're'grmdin or replacement of the faulty lenses ilthejreby incurring added .expen'seto the manu- 'racturer'and inconvenienceto'the customer.

It is the prime object ofmy invention to pro- 7 vide means for overcoming the above objections and to enable the operator to easily, qilickly and accurately transcribe the desired indices or guide .lines upon the lenses inexact register with: the "given lines of the protractor.

2 Another object is to provide a device of the above character which will be simple in construction and operation and cheap to manufacture.

Another object is to provide in a device of the above character means for easily and quickly adapting the same to varying thickness and types of lenses. I

Other objects and advantages will appear hereinafter and, while I have shown and will describe the preferred form of my invention, it will be understood that I do not limit myself to such preferred form but that various changes and adaptations may be made therein without departing from the spirit of my invention.

In the drawings accompanying and forming a part hereof:

Fig. 1 is a top plan of a protractor constructed according to my invention.

of my protractor.

Referring to the drawings (Figs. 1 and 2) I 0 indicates an annular base or support adapted to be positioned upon a bench or table and having oppositely disposed radially extending L-shaped arms II and I2 projecting from the outer periphery thereof. Rigidly mounted at its lower end l3 in the base In, centrally thereof, to extend upwardly therefrom, is a screwthreaded pintle bolt [4. A table I5 is mounted immediately above base l0, concentric therewith and is provided with a downwardly depending concentric hub l6, which is interiorly screwthreaded for operative engagement with the pintle bolt l4, by means of which said table is rotatably supported above said base and is also capable,

thru the, medium of the screwthreads, of being raised or lowered relatively thereto. a

Pivotally mounted in one of the arms I2 is a lever I! the outer end of which terminates in a finger piece l8 and secured upon the other or inner end thereof is a brake shoe 19 which. is

arranged to bear against the side wall 20 of the table [5, a spring 2! acting to normally hold said brake in its operative position to hold said table in any adjusted position against rotation. Slidably mounted in the upper end of the arm II, to project from either side thereof, is a screwthreaded stud 22 to the inner end of which is permanently secured one end of a Wire 23, preferably steel music wire altho any other suitable material may be used, the other end of which wire is secured to the upper end of the other arm I2. On the outer end of the stud 22 is provided a screwthreaded thumb nut 24 by means of which the tension of the wire 23 may be controlled.

Formed in the upper face of the table I is the protractor 25 which is usually a circle crossed with numerous degree lines radiating from the center to the outer edge and numbered at their outer ends to indicate the angle formed with the horizontal or zero line.

In the use of this form of my device the lens to be laid out will be positioned centrally of the protractor with its horizontal line coinciding with the horizontal or zero line thereof.

The brake is then disengaged and the table,

(and with it the lens) is rotated until the degree line representing the plane of the cylinder coincides with the index wire 23 and the brake is permitted to again engage the table and lock the same in its adjusted position.

Using the index wire 23 as a guide a pen or other marking instrument is used to scribe a line on the face of the lens coinciding with the 'degree line of the protractor.

' 1 To change the relative vertical positions of the In Fig. 3 I have shown another form of my device wherein the table and guide wire are adjustable independently of each other. e

In thisform I provide a base 21 from which "extends upwardly centrally thereof a screwthreaded pintle bolt 28, upon which is screwthreadedly mounted the protractor table 29 so as to be adjustable vertically, a set screw 39 be- ..in g provided for locking said pintle bolt and table against relative movement and lock said table in its adjusted position vertically.

"Immediately below the table 29, pintle bolt 23 is enlarged to form a journal 3I upon which is rotatably mounted the index Wirecarrier 32.

Member 32 is substantially U-shaped in side eleyation, is mounted about centrally of its base brakemember carried by the leg 34 provides 'means for securing table 29 and member 32 against accidental relative movement.

Projecting through the upper end of the leg: 33 to extend beyond each side thereof is a screwthreaded stud 38to the inner end of which is secured one end of the line wire 31. The outer brake as will be released from7'5 A threaded thumb nut 38 table and guide Wire to compensate for various thicknesses of lens the table is rotated in the" necessary direction to move the same up or k down upon the screwthreads.

upon the journal 3I and its legs 33 and 34 6X tend. upwardly on opposite sides of table-29. A

contact with table 29 and the index wire carrier 32 may be rotated upon journal 3| to bring the wire 31 into register with any of the lines upon the protractor table 29. Release of pressure upon the finger piece 39 will permit the spring III to force the brake 35 into contact with the table 29 and hold the same against movement relative to Wire carrier 32.

In Figs. 4 to '7 inclusive, III] indicates a rectangular block of wood, plastic, metal or any other desired material upon the upper face of which is permanently positioned the protractor I I I by means of screws or otherwise.

Formed in the underside of the block III) on the longitudinal center thereof is a rectangular groove or channel II2 the ends of which register with the lower ends of similar vertically extending grooves H3 and H4 in the opposed edges H5 and II6 of block H9, and mounted within these grooves by means of screws IIIJa is a substantially U-shaped member II! the upstanding legs H8 and H9 of which extend for a distance above the upper face of block II 0. Provided in the upper end of the leg H8 of member III are a plurality of equally spaced holes I20 in vertical alinement.

Formed in the upper end of the leg II9 of member II? is a notch I2I and immediately below this notch are provided a plurality of transverse slits I22 the inner termination of these slits coinciding vertically with the notch I2I.

Slidably positioned within one of the holes I20 in leg IIB, to project from each side thereof, is

a screw threaded rod I 23 on the outer end of which is positioned a screw threaded thumb nut I23a. Rigidly Secured to the inner end of rod I23 centrally thereof is one end of a wire I24, preferably of steel music wire, altho any other suitable material may be used.

' Wire I24 is positioned to extend between the legs I I8 and H9 with its free end passing thru the notch I2I in leg II9 then downwardly along the outer sidev of said leg into engagement with the clamp screw I25 which holds the same securely against displacement.

It will be understood that the position of wire I24 relative to the cutting or horizontal line legs H8 and I I9 is to permit of raising or lower- "'ing wire I24 to compensate for varying thickness and shapes of lenses.

The thumb nut I23a and rod I23 are provided for adjusting the tension 4 of wire I24.

In Figs. 8 and 9, I have shown another form of protractor adapted for use with my device. In this form I provide a central arcuate or concaved recess I29 of a size to easily accommodate the maximum size lens both as to depth and diameter and projecting upwardly from this re- 1 cessare a plurality of spaced studs I30 the upper ends of whichare adapted to support the lens to be laid out, these studs being of a height such as to correctly support lenses of. varying depth or radius above the protractor.

' In Fig. 10 is shown the protractor as being convexed instead of concaved.

The studs I30 may be omitted if desired or found advisable.

' Having described my invention, what I claim is: An ophthalmic protractor comprising a stationary base, an exteriorly screwthreaded stud immovably mounted at its lower end in said base to extend upwardly therefrom; a lens supporting table screwthreadedly mounted upon said stud concentric therewith whereby rotation of said table will raise or lower the same relative to said base; a protractor inscribed upon the upper face of said table; a pair of diametrically opposed, substantially L-shaped arms extending outwardly and upwardly from said base and terminating at a distance above said table; a brake member yieldably mounted upon one of said arms arranged to bear against the side Wall of said table and prevent relative movement between said base and table; a guide wire extending between the upper ends of said arms across said table; and means for controlling the tension of said wire.

E. W. LAISNE.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 

